The boy was sent from his grandmothers to the lab, which is across the river. He is bringing francium, a very explosive element when it reacts with water, on him. I can assure you, If he wasnt holding it, he'd be true to his word and kick their *ss easily. Probably would one shot most of them. As you can tell though, when he starts to lose his balance, thats when he gets frantic, because he doesnt want to get blown up.

Anyway, as for him saying "ow" thats because the paintball paint has some water in it, causing small detonations with the element. No ordinary bullet, and especially not a paintball, could actually hurt a being such as himself.

It is from one of the "man with no name trilogy" directed by sergio leone, and music composed by Ennio Morricone. The trilogy consists of A Fist Full of Dollars (A remake of Kurasawa's Yojimbo), For Few Dollars More, and The Good the Bad and the Ugly. All westerns and more specificly spaghetti westerns. /cue 'The More You Know" jingle.